I have built a talk box, I spare you the details, it functions as an all it one unit, ie - it has the power amp to drive the horn driver and the mic pre-amp for return feed. It works great so long as I use a pre-amp effect such as overdrive/distortion/fuzz etc. before driving the horn driver.

I am looking into including an adjustable effect such as the ones above, the question here is, what effect would best for the given situation?

I am gravitating towards a fuzz/hi-gain on the grounds that my technological knowledge tells me the driver has a high frequency low end cut off.